Double-wire electro-gas welding method

Abstract

The invention relates to the technical field of electro-gas welding, and particularly discloses a double-wire electro-gas welding method which comprises the following steps: arranging a butt joint seam between a first welding part and a second welding part; the rear side of the butt joint seam is blocked; direct current positive connection is conducted on a first welding wire, direct current reverse connection is conducted on a second welding wire, the first welding wire and the second welding wire are both arranged in a butt joint seam, and the first welding wire is located on the rear side of the second welding wire; and the first welding wire and the second welding wire are controlled to synchronously and periodically swing in the front-back direction and synchronously move upwards. According to the double-wire electro-gas welding method, groove machining is not needed, the stability of a welding pool is improved, and the welding quality is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of gas-electric vertical welding technology, and in particular to a dual-wire gas-electric vertical welding method. Background Technology

[0002] Gas-electric vertical welding is an arc welding method combining gas metal arc welding and electroslag welding technologies, belonging to the welding process in vertical or near-vertical positions. Current dual-wire gas-electric vertical welding methods, for example, as disclosed in publication number CN115026388A, published on September 9, 2022, disclose a high-transfer-coefficient, ultra-high heat input dual-wire gas-electric vertical welding method. During welding, the root-side welding wire remains fixed, while the face-side welding wire oscillates back and forth in a zigzag pattern along the groove depth and width directions. Existing technologies have at least the following drawbacks: a) Both welding wires use DC reverse polarity (welding wire connected to the positive terminal, workpiece connected to the negative terminal). The electromagnetic fields generated by the two energized welding wires and the two welding arcs are in the same direction, repelling and interfering with each other, adversely affecting the stability of the welding arc and the weld pool. b. Because the root-side welding wire does not oscillate and is far from the edge of the bevel, the arc heating area cannot effectively cover the root of the bevel. To ensure fusion at the bevel root perimeter, it is necessary to significantly increase the welding current and voltage of the root-side welding wire, which leads to a significant increase in welding heat input, causing coarsening of the weld metal and heat-affected zone microstructure, and a subsequent decrease in mechanical properties. In addition, the lack of oscillation of the root-side welding wire means that the arc's stirring effect on the molten pool is weakened, resulting in an increased temperature gradient in the molten pool (uneven heat distribution). The resulting weld microstructure has poor uniformity, making it difficult for harmful impurities (such as S and P) in the weld pool to be evenly distributed or float to the surface and escape. They are more likely to accumulate in the center of the weld, forming regional segregation, which increases the weld's sensitivity to hot cracking in the later stages of crystallization, ultimately affecting the quality of the weld. Summary of the Invention

[0003] The purpose of this invention is to provide a dual-wire gas-electric vertical welding method that eliminates the need for beveling, improves the stability of the weld pool, and ensures welding quality.

[0004] To achieve the above objectives, the present invention provides a dual-wire gas-electric vertical welding method, comprising: A butt joint is provided between the first welded component and the second welded component; Seal the rear side of the joint; The first welding wire is connected to DC positive polarity, and the second welding wire is connected to DC negative polarity. Both the first welding wire and the second welding wire are placed in the butt joint, and the first welding wire is located behind the second welding wire. The first and second welding wires are controlled to swing synchronously and periodically in the front-back direction and move upward synchronously.

[0005] In some embodiments, the mass percentage of the first welding wire is: C: 0.03-0.04%, Si: 0.06-0.08%, Mn: 0.7-0.9%, P: 0.007-0.009%, S: 0.009-0.011%, Ni: 0.02-0.04%, Mo: 1.03-1.05%, with the balance being Fe; the mass percentage of the second welding wire is: C: 0.02-0.03%, Si: 0.1-0.12%, Mn: 0.8-0.95%, P: 0.007-0.009%, S: 0.006-0.008%, Ni: 2.4-2.6%, Mo: 0.12-0.15%, with the balance being Fe.

[0006] In some embodiments, setting a butt joint between the first welded component and the second welded component includes: fixing the first welded component and the second welded component by means of a connector, and aligning the first welded component and the second welded component in the left-right direction to form the butt joint.

[0007] In some embodiments, sealing the rear side of the butt joint includes: passing a ceramic gasket through the clearance hole of the connector, allowing the front side of the ceramic gasket to abut against the rear sides of the first weld and the second weld, and sealing the rear side of the butt joint.

[0008] In some embodiments, before the ceramic gasket passes through the clearance hole of the connector, the front side of the ceramic gasket is covered with fiberglass cloth, and a metal housing is mounted on the rear side of the ceramic gasket.

[0009] In some embodiments, after passing the ceramic gasket through the clearance hole of the connector, a wedge is inserted between the rear side of the metal housing and the connector.

[0010] In some embodiments, controlling the first welding wire and the second welding wire to swing synchronously and periodically in the front-back direction and move synchronously upward includes: installing the first welding wire on the first welding gun, installing the second welding wire on the second welding gun, the oscillator driving the first welding gun and the second welding gun to swing synchronously and periodically in the front-back direction through the crossbeam, the lifting trolley driving the oscillator to move upward, and driving the copper slider to move synchronously upward against the front side of the butt joint.

[0011] In some embodiments, the minimum distance between the first welding wire and the ceramic backing is 15-25 mm, and the minimum distance between the second welding wire and the copper slider is 10-20 mm.

[0012] In some embodiments, the welding current of the first welding wire is 300-350A and the welding voltage is 30-34V; the welding current of the second welding wire is 380-420A and the welding voltage is 36-40V.

[0013] In some embodiments, the oscillation amplitude of the first welding wire and the second welding wire is 15-30mm, the end dwell time is 1-2s, and the welding speed is 6-15cm / min.

[0014] This invention provides a dual-wire gas-electric vertical welding method, which has the following advantages compared with the prior art: A butt joint is set between the first and second welded parts, eliminating the need for beveling and thus improving welding efficiency.

[0015] The first welding wire is connected to DC positive polarity, and the second welding wire is connected to DC negative polarity. Both the first and second welding wires are placed in the butt joint, with the first welding wire located behind the second welding wire. The polarities of the first and second welding wires are opposite, and the electromagnetic fields generated during the welding arc are in opposite directions, avoiding mutual repulsion and interference, and ensuring good stability of the welding arc and the weld pool.

[0016] The first and second welding wires oscillate synchronously and periodically in the front-to-back direction, and move upwards in sync. The welding arc of the first welding wire is close to the edge of the butt joint, so it does not require a larger welding current or voltage (resulting in low heat input and excellent mechanical properties of the weld and heat-affected zone) to ensure the fusion quality of the rear perimeter of the butt joint. Furthermore, the synchronous oscillation of the first welding wire provides necessary stirring, resulting in a small temperature gradient in the weld pool (relatively uniform heat distribution and minimal differences in the mechanical properties of the weld metal after crystallization). This reduces the accumulation of harmful impurities such as sulfur (S) and phosphorus (P) towards the weld center, minimizes regional segregation, and reduces the tendency for hot cracks to form in the weld center, thus ensuring weld quality. Attached Figure Description

[0017] Figure 1 A flowchart of a dual-wire gas-electric vertical welding method provided in an embodiment of the present invention.

[0018] Figure 2 This is a top view schematic diagram of the dual-wire gas electric vertical welding method provided in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the centerline cross-section along the front and rear directions of the butt joint of the dual-wire gas-electric vertical welding method provided in an embodiment of the present invention.

[0020] In the figure: 1. First welded component; 2. Second welded component; 3. Butt joint; 4. First welding wire; 5. Second welding wire; 6. Connector; 7. Ceramic gasket; 8. Relief hole; 9. Wedge block; 10. First welding torch; 11. Second welding torch; 12. Crossbeam; 13. Copper slider; 14. Solid weld; 15. Weld pool. Detailed Implementation

[0021] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0022] It should be understood that in the description of this application, the terms "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. That is, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, unless otherwise stated, "a plurality of" means two or more.

[0023] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0024] like Figures 1-3 As shown, the dual-wire gas-electric vertical welding method of this invention includes the following steps: S1. A butt joint 3 is provided between the first welded part 1 and the second welded part 2; thus, no beveling is required, thereby improving welding efficiency. Furthermore, since the butt joint 3 between the first welded part 1 and the second welded part 2 has no beveling, the front side of the butt joint 3 can be completely fused with the weld pool 15, avoiding the situation where the width of the copper slider 13 formed by forced cooling is insufficient to cover the width of the front side of the butt joint 3, enabling the welding of the first welded part 1 and the second welded part 2 with greater thickness.

[0025] S2. Seal the rear side of the butt joint 3; this will help to shape the solid weld 14.

[0026] S3. The first welding wire 4 is connected to DC positive polarity, and the second welding wire 5 is connected to DC negative polarity. Both the first welding wire 4 and the second welding wire 5 are placed in the butt joint 3, with the first welding wire 4 located behind the second welding wire 5. Thus, the polarities of the first welding wire 4 and the second welding wire 5 are opposite. During the process of generating a welding arc, the electromagnetic fields generated are in opposite directions, avoiding mutual repulsion and interference, and ensuring good stability of the welding arc and the weld pool 15.

[0027] S4. Control the first welding wire 4 and the second welding wire 5 to oscillate synchronously and periodically in the front-back direction, and move upward synchronously. The welding arc of the first welding wire 4 is close to the edge of the butt joint 3. The first welding wire 4 does not require a larger welding current and welding voltage (small welding heat input, excellent mechanical properties of solid weld 14 and heat-affected zone) to ensure the fusion quality of the periphery of the rear area of ​​the butt joint 3. Moreover, the synchronous oscillation of the first welding wire 4 has the necessary stirring effect, making the temperature gradient of the weld pool 15 small (relatively uniform heat distribution, small difference in mechanical properties of weld metal after crystallization). The degree of accumulation of harmful impurities such as S and P in the weld pool 15 towards the weld center is small, the regional segregation is small, and the tendency of hot cracks to form in the weld center is small, thus ensuring the welding quality.

[0028] Based on the above method, there is no need for beveling, which improves the stability of the weld pool and ensures welding quality.

[0029] In some embodiments, the mass percentage of the first welding wire 4 is: C: 0.03-0.04%, Si: 0.06-0.08%, Mn: 0.7-0.9%, P: 0.007-0.009%, S: 0.009-0.011%, Ni: 0.02-0.04%, Mo: 1.03-1.05%, with the balance being Fe; the mass percentage of the second welding wire 5 is: C: 0.02-0.03%, Si: 0.1-0.12%, Mn: 0.8-0.95%, P: 0.007-0.009%, S: 0.006-0.008%, Ni: 2.4-2.6%, Mo: 0.12-0.15%, with the balance being Fe.

[0030] In this embodiment, the first welding wire 4 and the second welding wire 5 have different chemical compositions. Increasing the Ni content in the second welding wire 5 prevents insufficient toughness of the weld metal at the front. Increasing the Mo content in the first welding wire 4 reduces the degree of segregation in the weld center region, preventing coarse grain structure in the weld metal after crystallization and improving its crack resistance. Specifically, both the first welding wire 4 and the second welding wire 5 have a diameter of Φ1.6mm.

[0031] In some embodiments, setting a butt joint 3 between the first welded component 1 and the second welded component 2 includes: fixing the first welded component 1 and the second welded component 2 with a connector 6, and aligning the first welded component 1 and the second welded component 2 in the left-right direction to form a butt joint 3. Specifically, the connector 6 uses a clip for easy disassembly and installation.

[0032] In some embodiments, sealing the rear side of the butt joint 3 includes: passing a ceramic gasket 7 through the clearance hole 8 of the connector 6, allowing the front side of the ceramic gasket 7 to abut against the rear side of the first welded member 1 and the second welded member 2, thereby sealing the rear side of the butt joint 3. In this way, the ceramic gasket 7 can withstand high temperatures to ensure the sealing effect.

[0033] In some embodiments, before the ceramic gasket 7 passes through the clearance hole 8 of the connector 6, the front side of the ceramic gasket 7 is covered with fiberglass cloth, and a metal shell is installed on the rear side of the ceramic gasket 7. Thus, the fiberglass cloth improves the rear-side forming quality of the solid weld 14 and prevents molten pool leakage. The metal shell enhances the structural strength of the ceramic gasket 7.

[0034] In some embodiments, after the ceramic gasket 7 is passed through the clearance hole 8 of the connector 6, a wedge 9 is inserted between the rear side of the metal housing and the connector 6. In this way, the ceramic gasket 7 is firmly pressed against the rear side of the first weldment 1 and the second weldment 2 by the action of the wedge 9, ensuring that it will not shift during the welding process.

[0035] It should be noted that when the height of the first welded component 1 and the second welded component 2 is relatively high, and multiple ceramic gaskets 7 are required, the ceramic gaskets 7 should be installed and fixed one by one from bottom to top, and the adjacent ceramic gaskets 7 should be in full contact and pressed tightly together. This effectively prevents the high-temperature liquid metal during the welding process from leaking or flowing from the gaps between the two adjacent ceramic gaskets 7, as well as between the ceramic gaskets 7 and the first welded component 1 and the second welded component 2, ensuring the continuity of the welding process and the good forming quality of the solid weld 14.

[0036] In some embodiments, controlling the first welding wire 4 and the second welding wire 5 to oscillate synchronously and periodically in the front-to-back direction, and to move synchronously upward, includes: mounting the first welding wire 4 on the first welding torch 10, mounting the second welding wire 5 on the second welding torch 11, the oscillator driving the first welding torch 10 and the second welding torch 11 to oscillate synchronously and periodically in the front-to-back direction via the crossbeam 12, the lifting trolley driving the oscillator to move upward, and driving the copper slider 13 to move synchronously upward against the front side of the butt joint 3. Thus, vertical welding is achieved. During the upward movement of the first welding wire 4 and the second welding wire 5, the copper slider 13 always stays against the front side of the butt joint 3 and moves synchronously upward, serving as a forming and cooling constraint.

[0037] In some embodiments, the minimum distance between the first welding wire 4 and the ceramic backing 7 is 15-25 mm, and the minimum distance between the second welding wire 5 and the copper slider 13 is 10-20 mm. This facilitates the creation of a reasonable thermal field distribution and arc pressure gradient.

[0038] In some embodiments, the welding current of the first welding wire 4 is 300-350A and the welding voltage is 30-34V; the welding current of the second welding wire 5 is 380-420A and the welding voltage is 36-40V. This achieves a balance between reliable fusion and efficient filling of the weld pool 15, while suppressing electromagnetic interference.

[0039] In some embodiments, the oscillation amplitude of the first welding wire 4 and the second welding wire 5 is 15-30 mm, the end dwell time is 1-2 s, and the welding speed is 6-15 cm / min. This homogenizes the weld pool 15, suppresses segregation, and improves the formation of the solid weld 14. The end dwell time refers to the time the first welding wire 4 and the second welding wire 5 remain at their foremost and last ends, respectively.

[0040] During the welding process of the butt joint 3 from bottom to top, a solid weld 14 is formed at the bottom, and a weld pool 15 is formed above the solid weld 14. Simultaneously, the front side of the weld pool 15 is sealed as the copper slider 13 moves upward. A cooling water pipe is installed inside the copper slider 13 for cooling. A carbon dioxide gas pipe is installed on the copper slider 13 to provide gas protection for the weld pool 15.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for dual-wire gas-electric vertical welding, characterized in that, include: A butt joint is provided between the first welded component and the second welded component; Seal the rear side of the joint; The first welding wire is connected to DC positive polarity, and the second welding wire is connected to DC negative polarity. Both the first welding wire and the second welding wire are placed in the butt joint, and the first welding wire is located behind the second welding wire. The first and second welding wires are controlled to swing synchronously and periodically in the front-back direction and move upward synchronously.

2. The twin-wire gas-electric vertical welding method according to claim 1, characterized in that, The first welding wire has the following mass percentages: C: 0.03-0.04%, Si: 0.06-0.08%, Mn: 0.7-0.9%, P: 0.007-0.009%, S: 0.009-0.011%, Ni: 0.02-0.04%, Mo: 1.03-1.05%, with the balance being Fe; the second welding wire has the following mass percentages: C: 0.02-0.03%, Si: 0.1-0.12%, Mn: 0.8-0.95%, P: 0.007-0.009%, S: 0.006-0.008%, Ni: 2.4-2.6%, Mo: 0.12-0.15%, with the balance being Fe.

3. The twin-wire gas-electric vertical welding method according to claim 1, characterized in that, Setting a butt joint between the first welded component and the second welded component includes: fixing the first welded component and the second welded component by means of a connector, and aligning the first welded component and the second welded component in the left-right direction to form the butt joint.

4. The twin-wire gas-electric vertical welding method according to claim 3, characterized in that, Sealing the rear side of the joint includes: passing a ceramic gasket through the clearance hole of the connector, allowing the front side of the ceramic gasket to abut against the rear side of the first welded part and the second welded part, and sealing the rear side of the joint.

5. The twin-wire gas-electric vertical welding method according to claim 4, characterized in that, Before passing the ceramic gasket through the clearance hole of the connector, cover the front side of the ceramic gasket with fiberglass cloth and install a metal shell on the rear side of the ceramic gasket.

6. The twin-wire gas-electric vertical welding method according to claim 5, characterized in that, After passing the ceramic gasket through the clearance hole of the connector, insert the wedge between the rear side of the metal housing and the connector.

7. The twin-wire gas-electric vertical welding method according to claim 4, characterized in that, Controlling the first welding wire and the second welding wire to swing synchronously and periodically in the front-back direction and move synchronously upward includes: installing the first welding wire on the first welding gun, installing the second welding wire on the second welding gun, the oscillator driving the first welding gun and the second welding gun to swing synchronously and periodically in the front-back direction through the crossbeam, the lifting trolley driving the oscillator to move upward, and driving the copper slider to move synchronously upward against the front side of the butt joint.

8. The twin-wire gas-electric vertical welding method according to claim 7, characterized in that, The minimum distance between the first welding wire and the ceramic backing is 15-25mm, and the minimum distance between the second welding wire and the copper slider is 10-20mm.

9. The twin-wire gas-electric vertical welding method according to claim 1, characterized in that, The welding current of the first welding wire is 300-350A and the welding voltage is 30-34V; the welding current of the second welding wire is 380-420A and the welding voltage is 36-40V.

10. The twin-wire gas-electric vertical welding method according to claim 1, characterized in that, The oscillation amplitude of the first welding wire and the second welding wire is 15-30mm, the end dwell time is 1-2s, and the welding speed is 6-15cm / min.

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